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Method for shaping super-continuum spectrum by using cascaded optical fibers

A technology of supercontinuum and optical fiber, which is applied in the field of shaping ultra-wideband supercontinuum, can solve the problems that the spectral width and flatness of supercontinuum are difficult to meet at the same time, and the limitation of supercontinuum, so as to improve flatness, improve power, Realize the effect of spectral flatness and spectral width

Pending Publication Date: 2020-11-13
HUNAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the spectral width and flatness of supercontinuum are difficult to satisfy at the same time, which limits the practical application of supercontinuum.

Method used

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  • Method for shaping super-continuum spectrum by using cascaded optical fibers
  • Method for shaping super-continuum spectrum by using cascaded optical fibers
  • Method for shaping super-continuum spectrum by using cascaded optical fibers

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0014] A titanium sapphire laser source, the pulse of which is a femtosecond pulse, and the output wavelength is 795nm under the condition of 25°C. Use it as a pump light source, control its water cooling temperature at 25°C, and adjust its output power to 2600W. Its central wavelength (795nm, 375THz) is located in the anomalous dispersion region of the first-stage optical fiber.

[0015] figure 1 (a) is the experimental setup for cascading optical fibers to shape the supercontinuum, figure 1 (b) Schematic diagram of the experimental setup for supercontinuum generation from a single single-mode fiber. Two single-mode optical fibers (fiber 1 and optical fiber 2) were fused into a cascaded single-mode optical fiber through a fusion tapered machine with low loss, and the above-mentioned laser light sources were respectively injected into a section of 60 cm long cascaded optical fiber through the coupling system (No. First level: 40cm optical fiber 1, second level: 20cm optical...

Embodiment 2

[0019] Different from Example 1:

[0020] image 3 (a) Adjust the position of the second zero-dispersion frequency point (low-frequency zero-dispersion point) of the second-level optical fiber by adjusting the air aperture of the optical fiber and the size of the hole spacing, so that the flatness of the output spectrum increases with the zero-dispersion position change to change. The experimental results show that the best spectral flatness is 7.6 at the low-frequency zero-dispersion point of 251THz, which is the second zero-dispersion frequency of the second-stage optical fiber, which is located in the first fundamental frequency generated in the first section of cascaded optical fiber. When the first-order soliton is within the spectrum range of its fiber output end, the red-shifted soliton and the corresponding dispersion wave in the second-stage fiber can well fill the spectrum vacancy of the first-stage fiber at its output and improve the flatness of the spectrum. sex....

Embodiment 3

[0023] Different from Example 1:

[0024] image 3 (b) By changing the length of the second-level optical fiber, when the length of the second-level optical fiber is 20cm (wherein the length of the first-level optical fiber is 40cm), the flatness of the spectrum reaches the optimum of 7.6, and when the length of the optical fiber continues to increase, the output The flatness of the spectrum will not be significantly improved, but the transmission loss will be increased.

[0025]Experiments have found that as the length of the second-stage optical fiber increases, the flatness of the spectrum will be significantly improved and finally stabilized, so the appropriate fiber length can be selected according to needs to ensure good flatness and relatively small transmission loss.

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Abstract

The invention provides a method for obtaining an ultra-wide-band ultra-flat super-continuum spectrum in a mode of cascading two sections of single-mode photonic crystal fibers with two double-zero dispersion points respectively. A short-pulse laser light source is injected into a cascaded optical fiber with a certain length through a coupling system, an output signal is received by a spectrum analyzer, the central wavelength of the light source is located in an abnormal dispersion area of the first stage of the cascaded optical fiber, and the first stage of the optical fiber is a photonic crystal optical fiber with a wide zero dispersion frequency interval so as to greatly broaden the spectrum; and then the second-stage optical fiber is cascaded, and the position of a second zero dispersion frequency (low-frequency zero dispersion point) of the second-stage optical fiber is adjusted, so that the second-stage optical fiber is located in the spectral range of a first fundamental solitongenerated in the first-stage cascaded optical fiber at the optical fiber output end of the second-stage optical fiber, and the flatness of the spectrum is obviously improved. Meanwhile, the flatness of the spectrum can be adjusted by adjusting the pumping power and the length of the second-stage optical fiber. According to the method, the zero dispersion frequency position can be adjusted by changing the aperture size and the hole spacing of the optical fiber, the super-continuous spectrum is shaped in a targeted manner, the super-continuous spectrum in different frequency ranges is shaped selectively, and finally, the ultra-wideband ultra-flat super-continuous spectrum is obtained.

Description

technical field [0001] The invention relates to a method for shaping spectrum by using cascaded optical fibers, in particular to a method for shaping ultra-wideband supercontinuum. Background technique [0002] Supercontinuum light sources are highly practical in real life, such as optical coherent imaging, frequency measurement, material spectroscopy, measurement of group velocity and waveform, wavelength conversion in all-optical communication, and dense wavelength division multiplexing. The principle of broadening for short-pulse laser sources (such as femtoseconds, sub-picoseconds) is: when the pulse propagates in the anomalous dispersion region, it will be disturbed by nonlinear effects and group velocity dispersion, and split into many ground state solitons with different group velocities. At the same time, phase-matched dispersion waves will be generated in the normal dispersion region, and the solitons will continue to redshift under the action of stimulated Raman sc...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01S3/00H01S3/30
CPCH01S3/005H01S3/0057H01S3/302
Inventor 杨华荣继芳陈书圆黄颖
Owner HUNAN UNIV
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